Process for preparing organic silicate polymer

ABSTRACT

The present invention relates to a low dielectric material essential for a next generation electric device such as a semiconductor device, with a high density and high performance. In detail, the present invention provides: a process for preparing an organic silicate polymer comprising a polymerization step in the absence of homogenizing organic solvents, of mixing and reacting organic silane compounds with water in the presence of a catalyst to hydrolyze and condense the silane compounds, that is thermally stable and has good mechanical and crack resistance properties; and a coating composition for forming a low dielectric insulating film; and a process for preparing a low dielectric insulating film using the organic silicate polymer prepared according to the process, and an electric device comprising the low dielectric insulating film prepared according to the process.

BACKGROUND OF THE INVENTION

[0001] (a) Field of the Invention

[0002] The present invention relates to a low dielectric materialessential for a next generation electric device such as a semiconductordevice, with a high density and high performance. More specifically, thepresent invention relates to: a process for preparing an organicsilicate polymer that is thermally stable and has good mechanical andcrack resistance properties, and a coating composition for forming a lowdielectric insulating film; and a process for preparing a low dielectricinsulating film using the organic silicate polymer prepared according tothe process, and an electric device comprising the low dielectricinsulating film prepared according to the process.

[0003] (b) Description of the Related Art

[0004] The semiconductor industry is moving toward increasing devicecomplexity, requiring shrinking geometric dimensions and highercomponent integration with greater dimensional densities in integratedcircuit devices, e.g. memory and logic chips. This has led to anincrease in the number of wiring levels and a reduction in wiring pitchto increase the wiring density. Current leading-edge logic processorshave 7-8 levels of high density interconnect, and interconnect linewidths are scheduled to decrease to 0.1 μm around the year 2005.

[0005] As device dimensions shrink to less than 0.25 μm, propagationdelay, crosstalk noise, and power dissipation due toresistance-capacitance (RC) coupling become significant. The smallerline dimension increases the resistivity of metal wires, and the narrowintermetal spacing increases the capacitance between the metal wires.Thus, although the switching speed of devices will increase as thefeature size decreases, the interconnect delay becomes the majorfraction of the total delay and limits the overall chip performance.Accordingly, in order to prepare a chip having high speed, a conductorhaving a low resistance and a dielectric material having a lowdielectric constant should be used. In addition, the use of lowdielectric material can remarkably decrease the power dissipation andcrosstalk noise.

[0006] Recently, several semiconductor device manufacturers have puttest products on the market that show improvements in their performanceof 20% or more, using copper wiring with high electric conductivityinstead of using the conventional aluminum wiring. A shift to use of newmaterials that exhibit low dielectric constant performance, for use ininterconnects, has recently been undertaken. If the dielectric filmsbetween interconnect layers in integrated circuits can make use of thesematerials, the effect on operating speed will be the same as that whichresulted with the switch from aluminum to copper technology. Forinstance, if the dielectric constant of the dielectric material ischanged from 4.0 to about 2.5, IC operating speed will be improved byabout 20%.

[0007] The interlayer dielectric material used in semiconductorintegrated circuit devices is predominantly SiO₂, which is generallyformed using chemical vapor deposition (CVD) to withstand variousprocessing operations associated with the conditions under which adielectric is formed. The dielectric constant of silicon thermaloxidation films, which have the lowest dielectric constant, is on theorder of 4.0. Attempts have been made to reduce the dielectric constantby introducing fluorine atoms into an inorganic film deposited by CVD.However, the introduction of fluorine atoms in large amounts decreasesthe chemical and thermal stability, so the dielectric constant achievedin actual practice is on the order of 3.5. Fluorinated oxides canprovide an immediate near-term solution and a shift to new types ofinsulating materials with sub-3 dielectric constant may be required.

[0008] One class of candidates is organic polymers, some of which have adielectric constant of less than 3.0. Incorporating fluorine into suchorganic polymers is known to further lower the dielectric constant. Mostorganic polymers do not, however, posses the physico-chemical propertiesrequired for on-chip semiconductor insulation, particularly thermalstability and mechanical properties (sufficient to withstand back-endline-fabrication temperatures within the range of 400˜450° C.). Feworganic polymers are stable at temperature greater than 450° C. Theyalso have a low glass transition temperature and thus elasticity thereofremarkably decreases at high temperatures, and they have a very highlinear expansion coefficient. Since the temperature rises to 450° C.during semiconductor IC integration and packaging processes, theresulting low thermal stability and elasticity and high linear expansioncoefficient can deteriorate the reliability of the devices.

[0009] Recently, in order to solve thermal stability problems of organicpolymers, the development of organic silicate polymers using a sol-gelprocess has emerged. In particular, organic SOG (Spin On Glass), havinga dielectric constant in the range of about 2.7˜3.3, has been proposedfor use as interlayer dielectrics in which the side chain of an organiccomponent (an alkyl group such as methyl) is bonded to the backbondchain of a siloxane bond.

[0010] There have so far been known various methods for producingorganic silicate polymers such as polyalkylsilsesquioxane for use as aprotective film, an interlayer insulating film, etc. for electronicparts or semiconductor elements. General methods for the synthesis oforganic silicate polymers are to hydrolyze and condense a silaneprecursor in a single organic solvent or mixture of organic solvents.The structure of organic silicate polymers-has been reported as a randomstructure, ladder structure, cage structure, and partial cage structure.In particular, the polysilsesquioxane which contains 1.5 oxygen atomsper silicon atom has a high level of cage or ladder structure and poormechanical properties. For instance polymethylsilsesquioxane typicallyhas poor mechanical properties. It experiences crack formation duringprocessing unless the film is very thin (often <1 μm).

SUMMARY OF THE INVENTION

[0011] Accordingly, the present invention is made to solve theseproblems of the prior art, and it is an object of the present inventionto provide a process for preparing an organic silicate polymer that canform an insulating thin film having excellent crack resistance andmechanical strength.

[0012] It is another object of the present invention to provide acoating composition for forming a low dielectric insulating film and aprocess for preparing a low dielectric insulating film using an organicsilicate polymer having thermal stability, crack resistance andmechanical strength, prepared according to said process, and an electricdevice comprising the low dielectric insulating film for a metal wiringinterlayer, prepared according to said process.

[0013] In order to achieve these objects, the present invention providesa process for preparing an organic silicate polymer comprising:

[0014] a) a polymerization step, in absence of homogenizing organicsolvents, of mixing and reacting organic silane compounds with water inthe presence of a catalyst to hydrolyze and condense the silanecompounds. The organic silicate polymer in accordance of the presentinvention has a high level of unexpected network structure.

[0015] The process further can comprise:

[0016] b) an aging step of adding organic solvents to the polymerizationproduct obtained in the step a) and heating the product to age it.

[0017] The present invention also provides a coating composition forforming a low dielectric insulating film comprising:

[0018] a) organic silicate polymers prepared by the above processes; and

[0019] b) organic solvents The coating composition further can comprise:

[0020] c) an additive of one or more selected from a group consisting ofan agent for improving adhesion to a substrate, a stabilizer forlong-term storage, and surfactants.

[0021] The present invention further provides a process for preparing alow dielectric insulating film comprising steps of:

[0022] a) dissolving organic silicate polymers prepared by the aboveprocesses in an organic solvent and coating the resultant solution on asubstrate to prepare a thin film; and

[0023] b) drying the thin film, and curing the same at 300 to 500° C.

[0024] The present invention further provides an electric devicecomprising the low dielectric insulating film prepared according to theabove process.

BRIEF DISCRIPTION OF THE FIGURES

[0025]FIG. 1 is a Fourier Transform Infrared (FTIR) spectrum of the filmproduced by Example 2.

[0026]FIG. 2 is a Fourier Transform Infrared (FTIR) spectrum of the filmproduced by Comparative Example 2.

DETAILED DESCRIPTION AND THE PREFERRED EMBODIMENTS

[0027] The present invention will now be explained in more detail.

[0028] A process for preparing an organic silicate polymer of thepresent invention comprises the step of direct hydrolysis andcondensation reaction by mixing an organic silane compound and water inthe absence of an organic solvent.

[0029] The present invention provides a process for preparing an organicsilicate polymer, and a low dielectric resin composition useful as(e.g.) a resin composition capable of forming a uniform dielectric film.The mechanical strength of as-cured films formed in accordance withpresent invention is enhanced as compared to as-cured films formed frompreviously known organic silicate polymers that have high levels of acage and/or ladder structure.

[0030] The process of the present invention for preparing the organicsilicate polymer may comprise a direct hydrolysis and condensationreaction step (neat reaction), the step of mixing and reacting theorganic silane compound with water to hydrolyze and condense the organicsilane compound taking place in the absence of homogenizing organicsolvents, and thereby growing the organic silicate polymer to a specificmolecular weight. A homogenizing solvent may be added to the organicsilicate polymer prepared by the neat reaction to stop the reaction, orto grow the polymer further to a desired molecular weight.

[0031] Additionally, the process of the present invention may compriseany methods comprising direct hydrolysis and condensation reactions inthe absence of an organic solvent, i.e. a composition for an organicsilicate polymer may be prepared by the following methods (i) to (iv).

[0032] The process of the present invention can additionally comprise:

[0033] (i) adding an organic silicate polymer and catalyst in adetermined amount to an organic silane compound continuously orintermittently to hydrolyze and condense the mixture, adding theresulting mixture to in an organic solvent after a determined time afterthe reaction, and lowering the reaction temperature to stop the reactionand obtain an organic silicate polymer;

[0034] (ii) adding water and catalyst in a determined amount to anorganic silane compound continuously or intermittently to hydrolyze andcondense the mixture for a determined time, adding the resulting mixtureto an organic solvent, further reacting the mixture, and lowering thereaction temperature to stop the reaction and obtain an organic silicatepolymer;

[0035] (iii) adding water and catalyst in a determined amount to asilane compound continuously or intermittently to hydrolyze and condensethe mixture for a determined time, further adding at least one selectedfrom water, a silane compound, and a catalyst in a determined amount tothe resulting mixture and reacting it for a determined time, andlowering the reaction temperature to obtain the organic silicatepolymer; and

[0036] (iv) mixing and reacting an organic silane compound with waterand catalyst in a determined amount in the presence of an organicsolvent to thereby hydrolyze and condense the mixture and obtain anorganic silicate polymer, and mixing the organic silicate polymer withthe organic silicate polymer prepared from the methods of (i) to (iii)in a determined amount.

[0037] The organic silane compound used in said process for preparingthe organic silicate polymer includes, although it is not limited to, anorganic silane monomer comprising silicon, carbon, oxygen and hydrogen,and organic silane oligomers that can be prepared therefrom. Inaddition, the silane monomer or oligomer can be used alone or incombination at a specific ratio thereof to prepare the organic silicatepolymer. Preferably, a compound selected from a group consisting of acompound represented by the following Chemical Formula 1 and a compoundrepresented by the following Chemical Formula 2 can be used alone or incombination at a specific ratio thereof to prepare the organic silicatepolymer.

[0038] [Chemical Formula 1]

[0039] R¹ _(m)R² _(n)SiX_(4-m-n) (where each of R¹ and R² which may bethe same or different and each is a non-hydrolysable group, X is ahydrolysable group, and m and n are integers of from 0 to 3 satisfying0≦m+n≦3).

[0040] [Formula 2]

[0041] R³ _(p)Y_(3-p)Si-M-SiR⁴ _(q)Z_(3-q) (where each of R³ and R⁴which may be the same or different and each is a non-hydrolysable group,Y and Z which may be the same or different and each is an hydrolysablegroup, and p and q are integers of from 0 to 2).

[0042] In the Chemical Formula 1, each of R¹ and R² is independently:hydrogen; alkyl such as methyl, ethyl, propyl, butyl, or others;fluorine-containing alkyl group such as trifluoromethyl, trifluoropropylor others; alkenyl such as vinyl, allyl, or others; or aryl such asphenyl. The alkyl groups may be linear or branched. X is independently:hydrolysable group; halogen such as chlorine; alkoxy such as methoxy;ethoxy or propoxy; acyloxy such as acetoxy; or others. Although there isno particular limitation with respect to the functional group R¹, R² andX, it is more preferred that R¹ and R² are independently hydrogen, alkylor phenyl, and X is an alkoxy group. Some examples of Chemical Formula 1include tetraalkoxysilane, monoalkyltrialkoxysilane,dialkyldiakoxysilane, trialkylmonoalkoxysilane, trialkoxysilane,dialkoxysilane, monoalkyldialkoxysilane, a mixture thereof, etc.

[0043] In the Chemical Formula 2, each of R³ and R⁴ is independently:hydrogen; alkyl such as methyl, ethyl, propyl, butyl, or others;fluorine-containing alkyl group such as trifluoromethyl, trifluoropropylor others; alkenyl such as vinyl or allyl; or aryl such as phenyl. Y andZ are independently: hydrolysable group; halogen such as chlorine;alkoxy such as methoxy, ethoxy or propoxy; acyloxy such as acetoxy; orothers. Although there is no particular limitation with respect to thefunctional group R³, R⁴, Y and Z, it is more preferred that R³ and R⁴are independently hydrogen, alkyl or phenyl, and Y and Z are an alkoxygroup. Organic bridged unit M may be alkylene or phenylene, preferablymethylene, ethylene, propylene or phenylene, or a mixture thereof.

[0044] Solvents that may be used for a hydrolysis and condensation orfor film coating include any agent or mixture of agents that willdissolve the composition to form a homogeneous liquid mixture of theChemical Formula 1 and 2. The solvent used in the present inventionincludes aliphatic hydrocarbon solvents such as: n-pentane, isopentane,n-hexane, isohexane, cyclohexane and the like; aromatic hydrocarbonsolvents such as benzene, toluene, xylene, alkyl benzene, naphthaleneand the like; alcohol solvents such as methanol, ethanol, n-propanol,isopropanol, n-butanol, t-butanol, cyclohexanol, methylcyclohexanol andthe like; ether solvents such as tetrahydrofuran, 2-dimethyl dioxane,ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propyleneglycol monomethyl ether, propylene glycol monomethyl ether, propyleneglycol monoethyl ether and the like; ester solvents such as ethylformate, methyl acetate, ethyl lactate, diethyl carbonate, ethylenecarbonate, ethylene glycol monomethyl ether acetate, propylene glycolmonoethyl ether acetate, ethylene glycol diacetate and the like; andamide solvents such as N-methyl pyrrolidone, formamide, N-methylformamide, N,N-dimethyl formamide, N-ethyl formamide, N,N-diethylformamide, N-methyl acetamide, N-ethyl acetamide and the like.

[0045] Solvents that have been used in hydrolysis and condensation arecompletely removed after the reactions to obtain organic silicatepolymer as an oil or a powder, which can be dissolved in a film-formingsolvent and used, or the organic solvent that has been used inhydrolysis and condensation can be directly used for film-forming.

[0046] As the catalyst, an acid or a base may be used for the hydrolysisand condensation of silane compounds. However it is more preferable touse an acid for the direct hydrolysis and condensation reaction (neatreaction) to control reaction rate, while both acid and base catalystsmay be used for the hydrolysis and condensation of silane in thepresence of solvent. Examples of the catalysts used in the presentinvention include: inorganic acids such as hydrochloric acid,hydrofluoric acid, nitric acid, sulfuric acid, phosphoric acid and thelike; organic acids such as formic acid, acetic acid, propionic acid,butanoic acid, pentanoic acid, oxalic acid, maleic acid, malonic acid,butyric acid, sulfonic acid, phthalic acid, furamic acid, citric acid,tartaric acid and the like; inorganic bases such as ammonia, sodiumhydroxide, potassium hydroxide, calcium hydroxide and the like; andorganic bases such as pyridine, piperazine, piperidine, choline,dimethylamine, diethylamine, triethylamine, monoethanolamine,diethanolamine, triethanolamine, monomethyidiethanolamine,dimethylmonoethanolamine and the like. Other catalysts such as metalchelate compounds and salt catalysts may also be used in this invention.The amount of catalyst used in general is 0.001 to 1 mole, preferably0.5 moles or less, per mole of the sum of the silane compounds of theChemical Formulae 1 and 2.

[0047] There are no particular limitations on the reaction temperaturewhen the product is made to have a desired molecular weight. Thetemperature may preferably be not higher than the boiling point of theorganic solvent used, and may preferably be 0° C. to 100° C. in order tocontrol the molecular weight of the resultant hydrolyzed product. Thereare no particular limitations on the reaction time at the time ofhydrolysis and condensation, and the reaction may be completed at thetime the product reaches a stated molecular weight. It is usuallypreferred to set the molecular weight of the final product within arange of from 500 to 1,000,000 as a weight-average molecular weight. Ifthe molecular weight of a hydrolyzed condensate of the Chemical Formula1 or a mixture of Chemical Formula 1 and 2 is less than 500, it may bedifficult to form a uniform coating film, and if the molecular weight ofa hydrolyzed condensate is greater than 1,000,000, the condensatepolymer may become insoluble.

[0048] Furthermore, the aging-step, which is conducted by adding organicsolvents to the organic silicate polymer and heating to age it, ispreferably conducted at a temperature of 15 to 100° C.

[0049] The present invention's coating composition for forming aninsulating film is prepared by dissolving the organic silicate polymersmade by the above processes with organic solvents. If desired, variousadditives, such as an agent for improving the adhesion to a substrate, astabilizer for long-term storage, and a surfactant for uniform filmcoating, may be added to the composition of the present invention beforeforming a coating film in such an amount as will not impair the effectsof the present invention.

[0050] As a method for forming a coating film on a substrate, it ispreferred to employ a method wherein the composition of the presentinvention containing a solvent is coated on the substrate, followed byheating and drying to evaporate the solvent. Here the resin compositionis applied to a substrate by methods known in the art such as spincoating, dip coating, spray coating, flow coating, screen printing orothers. The coating method may suitably be selected depending on theshape of the substrate to be coated, the required film thickness, etc.When the composition of the present invention is to be applied to aninterlayer dielectric film for a semiconductor device, a spin coatingmethod is preferred, since the in-plane distribution of the filmthickness will thereby be uniform. The solid content concentration inthe solution, as the sum of the resin composition of Chemical Formula 1and Chemical Formula 2 may suitably be selected from the viewpoint ofthe desired viscosity of the solution or the thickness of the coatingfilm, within the range whereby the solid content dissolves.

[0051] To form a coating film, a curing step is required after coatingto evaporate the solvent and to further crosslink the partiallyhydrolyzed co-condensate of mixture of the resin Formulae 1 and 2. Theheating may be conducted as a single-step process or a step-wiseprocess. For a sufficient cure the partially hydrolyzed co-condensate ofthe mixture of resin Chemical Formulae 1 and 2 and to ensure thatunreacted alkoxysilyl groups or silanol groups will not remain, a finalcuring at a temperature of preferably from 300 to 500° C., morepreferably from 400 to 500° C., is required. Unreacted alkoxysilylgroups or silanol groups will be a factor for increasing the dielectricconstant of the coating film by themselves, and they may further be awater absorbing site, which causes an increase of the dielectricconstant by water. Accordingly, it is desirable not to let them remainin the coating film.

[0052] The coating produced by the method herein are used on anysubstrate such as a metal or a ceramic but it is particularly useful onan electronic substrate intended for use in manufacture of an electronicdevice, examples of which include: an integrated circuit (IC) devicesuch as a memory IC, logic IC or MMIC (monolithic microwave IC); ahybrid IC; an optical device such as a light emitting diode or acharge-coupled device; a display device such as a liquid crystal displaydevice and the like.

[0053] The coating film formed by the present invention is applied as abuffer coating film, a passivation film, or an interlayer dielectricfilm for an electronic device, whereby it is possible to attain highperformance in (e.g.) reducing the time of signal propagation delay of adevice by virtue of excellent electrical properties such as a lowdielectric constant and a high dielectric strength, and it is alsopossible to attain high reliability by virtue of excellent mechanicalproperties.

[0054] The organic silicate polymer prepared by the present inventionmay be useful as a matrix resin composition for preparing porousdielectric films. For instance a mixture of the organic silicate polymerprepared by the present invention and thermally labile polymers ororganic small molecules may be spin-coated and thermally cured toinitiate vitrification and decomposition of labile polymers or smallmolecules.

[0055] Now, the following examples are provided to illustrate thepresent invention. The detailed preparations fall within the scope of,and serve to exemplify, the more generally described methods set forthabove. These examples are presented for illustrative purposes only, andshould not used to limit the scope of this invention found in theclaims.

EXAMPLE 1

[0056] 0.67 ml of distilled water and 0.80 ml of 2 N hydrochloric acidwere mixed, and then 7.6 ml of methyltrimethoxy silane were added to themixture. The resultant was put into a reactor, maintained ata.temperature of 5° C., and reacted for 2 hours. The temperature wasthen elevated to room temperature and it was further reacted for 2hours. The reactant solution was then diluted with toluene solvent andwashed with water three or four times until it became neutral. Magnesiumsulfate was introduced into the obtained organic layer to completelyremove remaining water therein, and the solvent was completely removedfrom the obtained organic layer in a vacuum oven to obtain a solid phaseproduct.

[0057] (Preparation of Insulating Film)

[0058] 300 mg of the obtained powder was dissolved in methylisobutylketone such that the total solution amounted to 1.5 g. The obtainedsolution was filtered to remove impurities therefrom, and then it wasspin coated to obtain thin film, and it was dried and cured under anitrogen atmosphere to prepare an insulating film.

EXAMPLE 2

[0059] 3.5 ml of distilled water and 0.60 ml of 5 N hydrochloric acidwere mixed, and then 12.82 ml of methyltrimethoxy silane and 1.37 ml ofdimethoxydimethyl silane were slowly added to the mixture under anitrogen atmosphere. The resultant was put into a reactor, maintained atapproximately 5° C., and reacted for 2 hours, and then the temperaturewas elevated to room temperature and the reaction was further continuedfor 2 hours. 15 ml of tetrahydrofuran (THF) solvent was added to themixture, and then the temperature was slowly elevated and reaction wasfurther continued for 4 hours while heat-refluxing. The reactant wasdiluted with ether solvent and washed with water three or four timesuntil it became neutral. Magnesium sulfate was introduced into theobtained organic layer to completely remove remaining water therein, andthe solvent was completely removed from the obtained organic layer in avacuum to obtain a solid phase product.

[0060] (Preparation of Insulating Film)

[0061] The obtained powder was dried and cured by the same method as inExample 1 to prepare an insulating film.

EXAMPLE 3

[0062] 1.2 ml of distilled water and 0.7 ml of 2 N hydrochloric acidwere mixed, and then 6 ml of methyltrimethoxy silane and 1.06 ml ofbistrimethoxysilylethane were slowly added to the mixture under anitrogen atmosphere. The resultant was put into a reactor, maintained atapproximately 5° C., and reacted for 2 hours, and then the temperaturewas elevated to room temperature and the reaction was further continuedfor 2 hours. 15 ml of tetrahydrofuran (THF) solvent was added to themixture, and then the temperature was slowly elevated and reaction wasfurther continued for 4 hours while heat-refluxing. The reactant wasdiluted with ether solvent and washed with water three or four timesuntil it became neutral. Magnesium sulfate was introduced into theobtained organic layer to completely remove remaining water therein, andthe solvent was completely removed from the obtained organic layer in avacuum to obtain a solid phase product.

[0063] (Preparation of Insulating Film)

[0064] The obtained powder was dried and cured by the same method as inExample 1 to prepare an insulating film.

EXAMPLE 4

[0065] 4.05 ml of distilled water and 0.80 ml of 2 N hydrochloric acidwere mixed, and then 7.6 ml of methyltrimethoxy silane were slowly addedto the mixture under a nitrogen atmosphere. The resultant was put into areactor, maintained at 5° C., and reacted for 2 hours. 10 ml oftetrahydrofuran (THF) was added to the mixture, and then the temperaturewas slowly elevated and reaction was further continued for 4 hours whileheat-refluxing. The reactant was then diluted with toluene solvent andwashed with water three or four times until it became neutral. Magnesiumsulfate was introduced into the obtained organic layer to removeremaining water therein, and the solvent was completely removed from theobtained organic layer in a vacuum oven to obtain a solid phase product.

[0066] (Preparation of Insulating Film)

[0067] The obtained powder was dried and cured by the same method as inExample 1 to prepare an insulating film.

COMPARATIVE EXAMPLE 1

[0068] 7.6 ml of methyltrimethoxy silane and 0.67 ml of distilled waterand 10 ml of tetrahydrofuran (THF) solvent were mixed, and then 0.80 mlof 2 N hydrochloric acid was slowly added to the mixture under anitrogen atmosphere. They were reacted at room temperature for 30minutes, and then the temperature was slowly elevated and reaction wasfurther continued overnight while heat-refluxing. After reaction, thetemperature of the solution was again lowered to room temperature, andthen the solution was diluted with toluene solvent and washed with waterthree or four times until it became neutral. Magnesium sulfate wasintroduced into the obtained organic layer to completely removeremaining water therein, and the solvent was completely removed from theobtained organic layer in a vacuum oven to obtain a solid phase product.

[0069] (Preparation of Insulating Film)

[0070] The obtained powder was dried and cured by the same method as inExample 1 to prepare an insulating film.

COMPARATIVE EXAMPLE 2

[0071] 12.8 ml of methyltrimethoxy silane, 1.37 ml of dimethoxydimethylsilane, 3.5 ml of distilled water and 20 ml of tetrahydrofuran (THF)solvent were mixed, and then 0.6 ml of 5 N hydrochloric acid was slowlyadded to the mixture under a nitrogen atmosphere. They were reacted atroom temperature for 30 minutes, and then the temperature was slowlyelevated and reaction was continued overnight while heat-refluxing.After reaction, the temperature of the solution was lowered again toroom temperature, and then the solution was diluted with toluene solventand washed with water three or four times until it became neutral.Magnesium sulfate was introduced into the obtained organic layer tocompletely remove remaining water therein, and the solvent wascompletely removed from the obtained organic layer in a vacuum oven toobtain a solid phase product.

[0072] (Preparation of Insulating Film) The obtained powder was driedand cured by the same method as in Example 1 to prepare an insulatingfilm.

COMPARATIVE EXAMPLE 3

[0073] 6 ml of methyltrimethoxy silane, 1.06 ml of thebistrimethoxysilylethane and 15 ml of tetrahydrofuran (THF) were mixedand then 0.7 ml of 2N hydrochloric acid with 1.2 ml of distilled waterwas slowly added to the mixture under a nitrogen atmosphere. They werereacted at room temperature for 30 minutes, and then the temperature wasslowly elevated and reaction was further continued overnight whileheat-refluxing. After reaction, the temperature of the solution waslowered again to room temperature, and then the solution was dilutedwith ether solvent and washed with water three or four times until itbecame neutral. Magnesium sulfate was introduced into the obtainedorganic layer to completely remove remaining water therein, and thesolvent was completely removed from the obtained organic layer in avacuum oven to obtain a solid phase product.

[0074] (Preparation of Insulating Film)

[0075] The obtained powder was dried and cured by the same method as inExample 1 to prepare an insulating film.

COMPARATIVE EXAMPLE 4

[0076] 7.6 ml of methyltrimethoxy silane, 4.05 ml of distilled water and10 ml of tetrahydrofuran (THF) were mixed, and then 0.80 ml of 2 Nhydrochloric acid was slowly added to the mixture. They were reacted atroom temperature for 30 minutes, and then the temperature was slowlyelevated and reaction was continued overnight while heat-refluxing.After reaction, the temperature of the solution was lowered again toroom temperature, and then the solution was diluted with toluene solventand washed with water three or four times until it became neutral.Magnesium sulfate was introduced into the obtained organic layer tocompletely remove remaining water therein, and the solvent wascompletely removed from the obtained organic layer in a vacuum oven toobtain a solid phase product.

[0077] (Preparation of Insulating Film)

[0078] The obtained powder was dried and cured by the same method as inExample 1 to prepare an insulating film.

[0079] (Formation of Thin Film and Evaluation of Properties Thereof)

[0080] Organic silicate polymers prepared in the Examples 1-4 andComparative Examples 1-4 were manufactured into thin films and theproperties thereof were evaluated and are represented in Table 1.

[0081] Molecular weights (weight average molecular weight: Mw) wereobtained as relative molecular weight values using gel permeationchromatography (GPC) with polystyrene as a standard. The mechanicalproperties of thin films were measured by spin coating the polymers on2×2 inch Si wafers and curing them at 420° C. for 1 hour under N₂conditions. Hardness and modulus were measured using a Tribolndenterfrom Hysitron Inc. Crack resistance was measured by observing whether ornot cracks were generated when thin films of 1 μm thickness wereprepared under the same conditions as the above. TABLE 1 ComparativeComparative Comparative Comparative Example Example Example ExampleExample Example Example Example 1 2 3 4 1 2 3 4 Mw 18300 6500 9000 91008500 4200 26000 11000 Modulus 4.89 3.41 5.52 3.95 1.95 2.03 3.99 2.31Hardness 0.76 0.48 0.87 0.64 0.25 0.17 0.62 0.32 Crack No crack No crackNo crack No crack Crack Crack No crack Crack Resistance formed formedformed (1 μm)

[0082] The above Table 1 shows the insulating film prepared using theorganic silicate polymer prepared according to the present invention hasenhanced mechanical strength.

[0083]FIGS. 1 and 2 shows two peaks in the range of 1000 cm⁻¹˜1200 cm⁻⁴,corresponding to absorbance at a siloxane (Si—O—Si) “stretch”. FIG. 1shows a FTIR of a film produced by Example 2 with a much strongerabsorbance at about 1030 cm⁻¹, confirming that the film prepared byExample 2 contains a higher level of long chain network Si—O—Sistructures than the film produced by Comparative Example 2. Similarresults have been observed in other examples.

[0084] The insulating film prepared using the organic silicate polymerprepared according to the present invention, therefore, has excellentmechanical strength and crack resistance.

1. A process for preparing an organic silicate polymer comprising: a) apolymerization step, in absence of homogenizing organic solvents, ofmixing and reacting organic silane compounds with water in the presenceof a catalyst to hydrolyze and condense the silane compounds.
 2. Theprocess for preparing the organic silicate polymer according to claim 1,further comprising: b) an aging step of adding organic solvents to thepolymerization product obtained in the step a) and heating the productto age it.
 3. The process for preparing the organic silicate polymeraccording to claim 2, wherein a heating temperature of step b) is 15 to100° C.
 4. The process for preparing the organic silicate polymeraccording to claim 1, wherein the reacting of step a) is conducted at atemperature of 0 to 100° C.
 5. The process for preparing the organicsilicate polymer according to claim 1, wherein the organic silanecompound is one or more selected from a group consisting of: organicsilane monomers containing silicone, oxygen and hydrogen; organic silaneoligomers prepared from the organic silane monomers; and a mixturethereof.
 6. The process for preparing the organic silicate polymeraccording to claim 1, wherein the organic silane compound is one or moreselected from a group consisting of a compound represented by ChemicalFormula 1, a compound represented by Chemical Formula 2, organic silaneoligomers thereof, and a mixture thereof: R¹ _(m)R²_(n)SiX_(4-m-n)  [Chemical Formula 1]where each of R¹ and R² which maybe the same or different is a non-hydrolysable group, hydrogen, alkylgroup, fluorine-containing alkyl group, alkenyl, or aryl, X is ahydrolysable group, halogen, alkoxy, or acyloxy, and m and n areintegers of from 0 to 3 satisfying 0≦m+n≦3, and R³ _(p)Y_(3-p)Si-m-SiR⁴_(q)Z_(3-q) where each of R¹ and R⁴ which may be the same or differentis a non-hydrolysable group, hydrogen, alkyl group, fluorine-containingalkyl group, alkenyl, or aryl, Y and Z, which may be the same ordifferent, is a hydrolysable group, halogen, alkoxy, or acyloxy, M is anorganic bridged unit, alkylene, or phenylene, and p and q are integersof from 0 to
 2. 7. The process for preparing the organic silicatepolymer according to claim 1, wherein an amount of the catalyst of stepa) is 0.001 to 1 mole per 1 mole of the organic silane compounds.
 8. Theprocess for preparing the organic silicate polymer according to claim 1,wherein the catalyst of step a) is an acid catalyst.
 9. The process forpreparing the organic silicate polymer according to claim 1, wherein theorganic silicate polymer obtained in the step a) has a networkstructure.
 10. A coating composition for forming a low dielectricinsulating film comprising: a) organic silicate polymers prepared by theprocess of claim 1 or claim 2; and b) organic solvents
 11. The coatingcomposition according to claim 10, further comprising: c) an additive ofone or more selected from a group consisting of an agent for improvingadhesion to a substrate, a stabilizer for long-term storage, andsurfactants. 12 The coating composition according to claim 10, wherein amolecular weight of the organic silicate polymers of a) is 500 to1,000,000.
 13. The coating composition according to claim 10, whereinthe organic silicate polymers of a) have a network structure.
 14. Thecoating composition according to claim 10, wherein the organic solventis one or more selected from a group consisting of aliphatic hydrocarbonsolvent, aromatic hydrocarbon solvent, alcohol solvent, ether solvent,ester solvent, and amide solvent.
 15. A process for preparing a lowdielectric insulating film comprising steps of: a) dissolving organicsilicate polymers prepared by the process of claim 1 or claim 2 in anorganic solvent and coating a resultant solution on a substrate toprepare a thin film; and b) drying the thin film, and curing the same at300 to 500° C.
 16. An electric device comprising the low dielectricinsulating film prepared according to the process of claim 15.